Reciprocating pumps



OC. 4, 1966 P, s, ELQUDOFF ET AL 3275,39@

REC IPROCATING PUMPS Filed D60. 16, 1964 96 975 .Y n q INVENTORS PMM S.Biondo-ff ATTORNEYS United States Patent O 3,276,390 RECIPROCATING PUMPSPeter S. Blondoff, Whittier, Calif., and Alvin R. Reinarz,

Gainesville, Tex., assignors to Armco Steel Corporation, Middletown,Ohio, a corporation of Ohio Filed Dec. 16, 1964, Ser. No. 418,623 8Claims. (Cl. 10S- 153) This invention relates to reciprocating pumps andmore particularly to heavy duty pumps such, for example, as thoseemployed in the oil elds for water ooding and like purposes where highfluid pressures must be maintained for prolonged periods.

For such heavy duty applications, it is common practice to employreciprocating plunger pumps having a plurality of plungers arrangedside-by-side and all driven from a single crankshaft. In such pumps,each plunger is connected to a crosshead by an intermediate rod, and theplunger, intermediate rod and crosshead all work within cylindricalsurfaces which are arranged in axial alignment With each other.Ordinarily, such cylindrical surfaces are formed in an integral framemember and therefore can be bored on one machine with a single setting,so that substantially perfect coaxial alignment is attainable.Maintenance of such perfect alignment is not possible, however, in thecompleted assembly, since the plunger is associated with a surroundingliner and liner housing, and the intermediate rod is associated with arod seal. Though the two cylindrical bores which house the liner housingand rod seal, respectively, may be in perfect coaxial alignment, it isimpractical to assume that perfect alignment can also be achieved, inthe linal assembly, between the inner surface of the liner and the innerdiameter of the rod seal.

Despite the difculties involved in attempting to achieve coaxialalignment of such elements as the liner and plunger relative to thebores in the frame, such alignment is demanded if the plunger,intermediate rod and crosshead are to be rigidly interc-onnected, afeature which is highly desirable if the effects of impact are to beminimized during operation of the pump. Heretofore, no trulysatisfactory solution to these problems has been achieved, and it hasbeen the practice to adopt such compromises as the provision of a loosejoint, between the plunger and the intermediate rod, to compensate foraxial misalignments in the overall plunger assembly.

It is a general object of this invention to devise a structure,particularly applicable to heavy duty reciprocating plunger pumps,wherein the plunger, intermediate rod and crosshead are all rigidlyinterconnected, yet inherent small axial misalignments are tolerated.

Another object is to provide, for such pumps, a plunger assembly inwhich the crosshead, intermediate rod and plunger are all rigidlyinterconnected axially of the assembly, but provision is made forlateral flexing adequate to compenaste for axial misalignments in theassembly.

A further object is to provide an improved plunger assembly for heavyduty reciprocating pumps.

VYet another object is to provide, in a plunger pump of the typedescribed, means for assuring that, in the event of breakage in theplunger drive, the corresponding pump chamber will remain sealed, andthe other plunger units can continue normal operation without furthersignificant damage.

Stated generally, the invention employs a plunger in the form of a rigidsleeve, and a mandrel extending Within the sleeve and secured thereto,the mandrel being rigidly joined to lthe intermediate rod which is inturn fixed to the crosshead, provision being made for flexing of themandrel in response to the side or lateral loads which occur, duringoperation of the pump, as a result of un- 31,276,390' Patented Oct. 4,1966 ice avoidable minor axial misalignments. In certain embodiments,the mandrel is made in two parts, including a main mandrel body and anattaching bolt which forms an extension thereof Within the plungersleeve, and the attaching bolt is provided with a portion of reduceddiameter capable of fracturing in the event that excessive friction isencountered during the suction stroke of the plunger. In otherembodiments, the mandrel is made as an integral unit capable of flexingunder acceptable lateral loads and also including a special portion ofreduced diameter to assure breakage at that point in event of anexcessive frictional load during the suction stroke. In all cases,provision is made for free stroking of the broken mandrel duringcontinued operation of the pump, and for maintaining the interior of theplunger sealed so as to prevent loss of uid from the pump chamber as aresult of breakage `of the mandrel.

In order that the manner in which the foregoing and other objects areattained in accordance with. the invention can be understood in detail,particularly advantageous embodiments thereof will be described withreference to the accompanying drawings, which form a part of thisspecication, and wherein:

FIG. 1 is a fragmentary longitudinal sectional View, with some partsshown in side elevation, taken on the axis of one plunger assembly of aheavy duty multiple plunger pump constructed in accordance with oneembodiment of the invention;

FIG. 2 is a longitudinal sectional View, enlarged as compared to FIG. 1,of the plunger and cylinder arrangement of -the pump shown in FIG. 1;and

FIG. 3 is a view, similar t-o FIG. 2, illustrating a plunger andcylinder arrangement, useful in the pump of FIG. 1, constructed inaccordance with another embodiment of the invention.

Turning now to the drawings in detail, and lirst to FIGS. 1 and 2, theinvention is illustrated as applied to a heavy duty reciprocating pumpcomprising an integral, rigid frame member 1 and a iluid end assembly 2,the latter defining three pump chambers. A plunger assembly 3 isprovided for each pump chamber, each plunger assembly being driven by acrankshaft 4 through the combination of a crankpin 5, connecting rod 6,crosshead 7, intermediate rod S and plunger mandrel 9.

Frame member 1 is provided with a cylindrical bore 10, within which theplunger assembly and associated elements are disposed, a cylindricalbore 11 within which the crosshead 7 reciprocates, and a cylindricalbore 12 in which is mounted a rod seal 13. Since member 1 is rigid andintegral, bores 10-12 can be made with a single rnachine setting and,therefore, can be in virtually perfect axial alignment.

A bushing 14 is mounted in bore 10 and has an outwardly extendingannular end flange 15 engaged between a shoulder on the frame member andthe adjacent face of the lluid end assembly. The bushing has interiorthreads which engage exterior threads on the liner housing member 16.The liner housing member is disposed with one end directly abutting theadjacent face of the fluid end assembly and has an interior transverseannular shoulder 17 which faces toward the opposite end of the housingmember, the latter end being threaded exteriorly to accept the linearclamp or gland nut 18. Liner 19 is a cylindrical sleeve having one endheld in engagement with shoulder 17 by the action of nut 18. The linersleeve has an internal transverse annular groove 20 iconnected by radialports to an annular space 21 between the sleeve and housing member 16,the annular space 21 in turn being connected by radial ports to annularspace l 22 between the housing member and bushing 44. A suit-,

able tube 23 is connected to space 22 by fitting 24, theV tube leadingback to the suction side of the pump so that fluid leakage is returnedto the fluid end assembly.

Annular seals are provided between the liner sleeve and the housingmember at and 26, and between the housing member and bushing at 27. Theliner sleeve has an internal seal at 2S, between groove 20 and the endof the sleeve opposite the fluid end assembly. A seal 29 is providedbetween housing member 16 and the adjacent surface presented by thefluid end assembly.

The plunger 30 is generally in the form of a sleeve having a plaincylindrical outer surface 31. Commencing at the end of the plungernearer the crosshead, the plunger has portions 32, 33 and 34 ofprogressively smaller internal diameter, there being a transverseannular shoulder 35 between portions 33 and 34. At its other end, theplunger has a portion 36 of larger diameter than portion 34, there beinga transverse annular shoulder 37 between portions 34 and 36. With theplunger in assembled position in the pump, shoulder 35 faces toward thecrosshead while shoulder 37 faces toward the liuid end assembly.

In usual cases, the clearance between the plunger 30 and the linersleeve 19 is less than 1/1000 inch, so that the plunger is firmlyconstrained to a position which may or may not be -coaxial with respectto bores 10-12.

Mandrel 9 comprises an elongated shank 3S and an enlarged cylindricalhead 39, the latter having an outer diameter such as to Ibe snuglyembraced by plunger portion 33 and a transverse end face capable offlush engagement with shoulder 35. Head 39 has an axially extendingthreaded bore 40, the length of the bore being shorter than that of head39.

The mandrel 9 is secured to the plunger 30 'by a bolt 41 having acylindrical head 42 and a shank comprising two threaded portions 43 and44 separated by a portion 45 of reduced diameter. Of .a diameter to fitsnugly within portion 36 of the plunger, head 42 has a transverseannular outwardly opening groove which retains an O-ring or like sealingelement 46. Adjacent threaded portion 43, the bolt head presents atransverse annular shoulder capable of ilush engagement with shoulder 37of the plunger. Threaded portion 43 of the bolt is engaged with interiorthreads on portion 34 of the plunger adjacent shoulder 37, while thethreaded tip portion 44 of the bolt is engaged with the interior threadsof bore in the mandrel head. Accordingly, when the mandrel and plungerare assembled as seen in FIG. 2, the plunger portion 34 is securelyclamped between the Ibolt head 42 and the mandrel head 39, so that theplunger Iand mandrel are connected together with complete rigidityinsofar as axial loads in either direction are concerned.

Shank portion 45 of the bolt is of significantly smaller diameter thanany other portion of the mandrel assembly constituted by the mandrel`and bolt. Further, the internal diameter of plunger portion 34 islar-ger than the diameter of shank portion 45, so that there is anannular space surrounding shank portion 45 throughout the total lengththereof.

The shank 38 of mandrel 9 has a diameter which is small as compared tothe diameter of the intermediate rod 8. Also, the length of mandrelshank 38 is great as compared to the mandrel shank diameter, the ratioof length-to-diameter of the mandrel shank approaching 7:1 in theparticular embodiment illustrated. Accordingly, the shank of the mandrelprovides .a degree of limberness or exing ability in theplunger-mandrel-intermediate rod assembly which is adequate tocompensate for axial misalignments between plunger 30 and bores 10-12,lfor example. In this regard, it is to be noted that the internaldiameter of plunger portion 32, within which most of the len-gth of themandrel shank is accommodated, is considerably larger than the diameterof the mandrel shank, so that complete freedom for iiexing of themandrel shank is allowed.

At its end opposite head 39, mandrel 9 has an enlarged cylindricalportion 47, an outwardly projecting transverse annular flange 48 and anaxially projecting extension 49. The cooperating end of intermediate rod8 has an outwardly projecting transverse annular flange 50 of the samediameter as flange 48, and is provided with an axial rbore dimensionedto snugly accommodate extension 49. At flanges 50 and 4S, theintermediate rod and the mandrel have flat end faces 51 and 52,respectively, capable of flush engagement. The intermediate rod and themandrel are held rigidly together by a split clamp `53.

At its end opposite flange 50, the intermediate rod 8 is rigidly'connected to crosshead 7 `by an exteriorly threaded axial extension 54engaged in a threaded axial bore in the crosshead, the crosshead and theintermediate rod having abutting end faces 55 and 56, respectively.

From the foregoing, and with reference to FIG. l, it will be understoodthat the combination of crosshead 7, intermediate rod 8, plunger mandrel9, and plunger 30 is essentially rigid with respect to axial loads inboth directions, but that the shank 38 of the plunger mandrel provides acapacity to tiex or yield under such Ilateral stresses as may occurduring operation of the pump because of failure to achieve perfectcoaxial alignment of the moving and stationary parts with respect tobores 10-12.

In conventional fashion, the iluid end assembly 2 defines a suctionmanifold 60 and a discharge manifold 61 both common to all three pumpchambers. Each pump charnber is defined by a sleeve 62 which is open atits end adjacent the corresponding plunger 30 and closed at its otherend, sleeve 62 and plunger 30 4being coaxial Iand so dimensioned that,as the crankshaft 4 is driven, the plunger can reciprocate into and outof the pump chamber sleeve. Sleeve 62 has an inlet opening 63 and adischarge opening 64, and the usual inlet Valve 65 and outlet valve 66are provided. The flat annular face at the open end of sleeve 62 is inflush engagement with the corresponding liat end face of liner housingmember 16, and the seal 29 is accordingly best accommodated by a groovedefined jointly by members 62 and 16.

During normal operation, the plunger 30 reciprocates freely in liner 19as the crankshaft is driven, ,and operation of the pump proceeds inusual fashion, except that the plunger mandrel 9 flexes :to compensatefor (minor axial misalignments so that frictional wear is reduced, andthe axial rigidity of the plunger-mandrel-intermediate rod-crossheadassembly eliminates impacting on stroke reversals. In the event ofexcessive frictional loads, such as Would indicate impending seizure ofthe sliding surfaces, breakage will ocour in portion 45 of bolt 41,during the suction stroke, since portion 45 is the weakest part of thecombination of reciprocating elements. Upon occurrence of such breakage,the bolt head 42, with its seal 46, remains in place within plungerportion 36, being retained by threaded portion 43. Accordingly, the pumpchamber is completely sealed and operation of the pump can continue, theother plungers remaining effective. The broken plunger mandrel assemblywill, of course, continue stroking, but any further damage occurringbecause of such action will be limited to parts which are relativelyinexpensive and easily replaceable.

For ease of assembly, the head portion 42 of bolt 41 can be providedwith a polygonal socket for cooperation with a conventional tool.

In the embodiment of the invention shown in FIGS. 1 and 2, the linersleeve, the plunger, and the plunger mandrel are all of metal. FIG. 3illustrates a modified embodiment of Ithe invention which has the sameadvantages as that of FIGS. l and 2 but wherein the liner sleeve andplunger are of a nonmetallic material such as a suitable ceramic. Inthis embodiment, an integral metal housing member 75 is employed inplace of elements 14 and 16 of FIGS. 1 and 2. At one end, member 75 hasan annular outer flange 76 and a ilat end face 77 to allow clamping ofthe member to the fluid end assembly by an integral frame member, suchas member 1, FIG. l, a circular axially opening groove 78 being providedto accommodate a suitable seal. Member 75 has a cylindrical 'boreincluding a portion 79 of larger diameter and a portion 80 of smallerdiameter, an internal transverse annular shoulder 81 being providedbetween the two bore portions and facing away from end face 77.

The nonametallic :liner sleeve 82 is cylindrical, its outer surfacebeing embraced by bore portion 79 of the housing member and one end ofthe liner sleeve being in engagement with shoulder 81. The liner issecured rigidly to the housing member in any suitable conventionalfashion, the precise nature of which depends upon the particularnon-metallic material 'from which the liner sleeve is fabricated. Theliner is provided with an internal transverse annular groove 83 near endface 84, and a second groove 85 between end face 84 and groove 83.Groove 83 is of semicircular transverse cross section. A radial port 86is provided through the wall of the liner sleeve for communication witha port 87 in the housing member, so that the groove 83 can be placed incommunication with the suction side of the pump, as by tting 24 and tube23, FIG. l, and will serve to provide a iluid seal between the plungerand liner. Groove 85 retains a mechanical sealing element, such as anO-ring.

The plunger 88 can be fabricated `from a dilferent material or from thesame non-metallic material as is liner 82. Plunger 88 has a plaincylindrical outer surface 89 and a cylindrical central bore having aportion 91 of larger diameter, an intermediate portion 92 of distinctlyIsmaller diameter than portion 91, `and a portion 913 of a diameterslightly smaller than that of portion 92. A transverse annular shoulder94 is provided between bore portions 91 and l92 and faces theouter endof bore portion 91. The `outer end of bore portion 93 is closed, andsealed against entry of fluid, by a plug 95 which can be of the samematerial as is the plunger.

Fabricated of a suitable metal, the plunger mandrel 96 includes a shank97 extending between an intermediate enlarged portion 98 and one portion98 of a pin connection by which the mandrel is joined rto theintermediate rod (not shown). Beyond enlarged portion 98, the mandrelincludes a cylindrical tip portion 99 of a diameter equal to that ofplunger -bore 4portion 93, that diameter being significantly smallerthan the diameter of shank 97. Enlarged portion 98 presents avtransverse annular face 100 directed toward the free end of tip portion9.9. Tip portion 9-9 is substantially longer than is the intermediatebore portion 92 of the plunger.

Mandrel 96 is disposed coaxially lwith respect to plunger 88, the tipportion 99 extending through bore portion 92 and into lbore portion 93.The wall of bore portion 93 embrace-s tip portion L99 and the two partsare rigidly joined together at this point lin any suitable conventionalfashion. Shoulder 94 and face 100 are .in direct, ilush enga-gement. Thegreater portion of shank 97 is di-sposed within bore portion 91, there4being a substantial annular space between the shank and the mandrel. Asubstantial portion of the tip portion 99 of the mandrel is within Iboreportion 92 and there is a signiiicant annular space between tip portion`99 and the wall of bore portion 92.

Recognizing that the mandrel is to be connected to an intermedia-tedriving rod which is rigid and of relatively large diameter, as in thecase of rod 8, FIG. l, it will fbe understood that shank 97 i-s ofcomparatively small diameter and aiords a capability for iiexing undertolerable lateral loads in the same manner as does shank 318, lFIGS. 1and 2. Similarly, the part of tip portion 99 disposed within boreportion 92, being of still smaller diameter, provides a predeterminedpoint for breakage in the event that excessive frictional forces areencountered during a suction stroke of the plunger 88. In event ofbreakage at this point, the plunger remains within liner 82 and materiallos-s of `fluid from the pump chamber is prevented by plug and the sealsbetween the plunger and the liner. Operation of the pumi with continuedstroking of the broken mandrel, can thus continue.

Ilhrou'gh particularly advantageous embodiments of the invention havefbeen illustrated and described, it twill be understood that variouschanges and modificati-ons can be made therein without departing fromthe scope of the invention as defined in the appended claims.

What is claimed is:

1. `In a heavy duty reciprocating pump ofthe type comprising a rigidframe, a dluid end :assembly deiining a plurality of pump chambers, `aplurality of devices rigidly supported Iby the frame and each deiining acylindrical passage communicating with a different one of the pumpchambers, and drive 4means including a plurality of reciprocatorymembers each constrained to move along .the axis of a `different one ofthe cylindrical passages, the combination of a plurality of plungerassemblies each operatively arlranged in a different one of thecylindrical passages and each comprising a tubular plunger, a mandrelhaving a shank portion extending coaxially with said plunger, meanssecuring said mandrel rigidly to said plunger at the end of said shankportion disposed within said plunger, and means connecting the otherend` of said mandrel to one of the reciprocatory members of the drivemeans;

said shan-k portion having a transverse cross-section which is small ascompared to the cross-sectional size of the one of the reciprocatorymembers to which said mandrel is connected, whereby said shank portionaffords a limited flexing vability under misaligments affecting thereciprocatory movement of `said plunger,

said means securing said mandrel to said plunger including an elementwhich is interposed between said shank portion and said plunger andwhich is substantially Aweaker than said shank portion, said plungerdefining `a free annular space about said shank portion to allow flexingof said shank portion. 2. A pump according `to claim 1, wherein saidmeans securing said mandrel to said plunger cornprises a threadedfastener member 'having an enlarged head port-ion, a shank portion, anda threaded tip,

said plunger having an internal shoulder spaced axially from the end ofsaid mandrel which is disposed within said plunger,

said mandrel having a threaded bore within which said threaded tip ofsaid fastener member is engaged, said head portion `of said fastenermember being in engagement with said shoulder,

said shank portion of said fastener -member constituting element whichis interposed between said shank portion of said mandrel and saidplunger.

3. A pump according to claim 2 and further comprising annular seal meansbetween said head portion of said `fastener member and said plunger 'toestablish a fluid-tight seal effective to prevent loss of fluid from thepump chamber via the interior of said plunger in event of 'breakage ofsaid shank portion of said fastener member.

4. A pump according Ito claim 2, wherein said fastener member isthreaded adjacent said head portion for -screw-thread engagement withinternal threads on said plunger, such screw-thread engagement retainingsaid head portion of said fastener member in place in said plunger afterbreakage of said shank portion of said -fastener member.

7 5. A pump according to claim 1, wherein said plunger has two internaltransverse annular shoulders each facing toward a different end of saidplunger, `said mandrel thas a transverse `face engaged with one of saidshoulders, and said means securing said mandrel rigidly to said plungercomprises a fastener member having a head portion engaged with the otherof said shoulders. 6. A pump according to claim 5, wherein said fastenermember has la threaded tip engaged in screw-thread relation with athreaded portion of said mandrel, a .plain shank portion extending fromsaid mandrel toward said head portion, and a threaded portion disposed'between said plain shank portion and -said head portion and engaged inscrew-thread relation with internal threads on said plunger to yretainlsaid head portion in place in even-t of breakage of said plain shankportion. 7. A pump according to claim 1, wherein said plunger has an endportion of larger internal diameter, an intermediate portion of smallerinternal diameter, and a third portion of still smaller internaldiameter, there being a transverse annular shoulder between said endportion and said intermediate portion, rsaid shank portion of saidmandrel terminating at one end in a portion presen-ting a shoulderengaged with said transverse annular shoulder, `said mandrel including atip portion projecting from said one end of said shank portion throughsaid intermediate portion of said plunger int-o said third portion ofsaid plunger,

said .tip portion being rigidly axed to said third portion of -saidplunger, the transverse cross-section of said tip portion within saidintermediate portion of said plunger being significantly smaller thanthe cross-section of said shank portion. 48. A plunger assembly forheavy duty reciprocating pumps comprising, in combination,

8 a tubular plunger having an elongated end portion of larger internaldiameter,

an intermediate portion of 4an internal diameter smaller than saidelongated end portion, and

a second end portion having an internal diameter larger than saidintermediate portion,

said intermediate portion presenting a rst trans- -verse annularintern-a1 shoulder facing toward the open end of said elongated endportion and a second transverse annular internal shoulder facing towardthe open end of said second end portion,

a mandrel 'having a shank portion projecting axially through saidelongated end portion and terminating in means presenting a transverseannular shoulder engaged with said rst shoulder; and

a fastener member having a head portion, a shank, and

a threaded tip,

said head portion being disposed in said second end portion and engagingsaid second shoulder,

said threaded tip being engaged in a threaded bore in said mandrel, and

`said shank of said fastener member being disposed within saidintermediate portion off said plunger and having a transversecross-section substantially smaller than .the .transverse cross-sectionof said shank of said mandrel.

References Cited by the Examiner UNITED STATES PATENTS 1,115,180 10/1914Day et al. 103-169 1,328,474 1/1920 Astrom 103-153 2,585,544 2/1952Friedlander 103-169 2,752,214 6/1956 iFerris 103-153 2,766,701 10/1956`Giraudean 103-153 FOREIGN PATENTS 587,412 11/1959 Canada. 485,83110/1953 Italy.

MARK NEWMAN, Primary Examiner.

H. F. RADUAZO, Assistant Examiner.

1. IN A HEAVY DUTY RECIPROCATING PUMP OF THE TYPE COMPRISING A RIGIDFRAME, A FLUID END ASSEMBLY DEFINING A PLURALITY OF PUMP CHAMBERS, APLURALITY OF DEVICES RIGIDLY SUPPORTED BY THE FRAME AND EACH DEFINING ACYLINDRICAL PASSAGE COMMUNICATING WITH A DIFFERENT ONE OF THE PUMPCHAMBERS, AND DRIVE MEANS INCLUDING A PLURALITY OF RECIPROCATORY MEMBERSEACH CONSTRAINED TO MOVE ALONG THE AXIS OF A DIFFERENT ONE OF THECYLINDRICAL PASSAGES, THE COMBINATION OF A PLURALITY OF PLUNGERASSEMBLIES EACH OPERATIVELY ARRANGED IN A DIFFERENT ONE OF CYLINDRICALPASSAGES AND A EACH COMPRISING A TUBULAR PLUNGER A MANDREL HAVING ASHANK PORTION EXTENDING COAXIALLY WITH SAID PLUNGER, MEANS SECURING SAIDMANDREL RIGIDLY TO SAID PLUNGER AT THE END OF SAID SHANK PORTIONDISPOSED WITHIN SAID PLUNGER, AND MEANS CONNECTING THE OTHER END OF SAIDMANDREL TO ONE OF THE RECIPROCATORY MEMBERS OF THE DRIVE MEANS; SAIDSHANK PORTION HAVING A TRANSVERSE CROSS-SECTION WHICH IS SMALL ASCOMPARED TO THE CROSS-SECTIONAL SIZE OF THE ONE OF THE RECIPROCATORYMEMBERS TO WHICH SAID MANDREL IS CONNECTED, WHEREBY SAID SHANK PORTIONAFFORDS A LIMITED FLEXING ABILITY UNDER MISALIGMENTS AFFECTING THERECIPROCATORY MOVEMENT OF SAID PLUNGER, SAID MEANS SECURING SAID MANDRELTO SAID PLUNGER INCLUDING AN ELEMENT WHICH IS INTERPOSED BETWEEN SAIDSHANK PORTION AND SAID PLUNGER AND WHICH IS SUBSTANTIALLY WEAKER THANSAID SHANK PORTION, SAID PLUNGER DEFINING A FREE ANNULAR SPACE ABOUTSAID SHANK PORTION TO ALLOW FLEXING OF SAID SHANK PORTION